routes with iBGP

[Ondrej Zajicek]

On Tue, Jun 08, 2010 at 02:15:07PM +0200, Arjan Filius wrote:
> Hello bird-users,
>
> Running bird 1.2.3-ppa ubuntu 10.04,x64, on 2 hosts, internally connected 
> with 2 lines, and running 2 iBGP sessions, both routers have their own  
> GlobalTransit provider
>
> the iBGP protocols have no filters on both routers
>
> What is noticed (for example with network 40.0.40.0/21):
> router1:
> bird> show route 40.0.40.0/21
> 40.0.40.0/21       via <Transit1_BGPRTR1> on eth5 [Transit1_BGPRTR1_IPv4 2010-06-04 11:26:29] * (100) [AS4249i]
>                    via <Transit1_BGPRTR2> on eth5 [Transit1_BGPRTR2_IPv4 2010-06-04 11:26:39] (100) [AS4249i]
> bird>
>
> router2:
> bird> show route 40.0.40.0/21
> 40.0.40.0/21       via <gw1_router1> on eth1 [iBGP_IPv4_1 2010-06-08  13:39:27] * (100) [AS4249i]
>                    via <gw2_router1> on eth0 [iBGP_IPv4_2 2010-06-08  13:28:18] (100) [AS4249i]
>                    via <Transit2_BGPRTR1> on eth5 [Transit1_BGPRTR1_IPv4  
> 2010-06-04 11:26:30] (100) [AS4249i] bird>
>
> so router1 isn't showing it's route option to a transit on router2 (via 2 
> iBGP sessions)

>
> Is this correct, end if yes why?

It is correct because in router2, iBGP route received from router1 is
primary and therefore it is not exported back back to router1 (and only
the primary route is exported).

But the question is why internal route is primary (usually, external
routes are primary). Could you send the output of 'show route 40.0.40.0/21 all'
on router2?

-- 
Elen sila lumenn' omentielvo

Ondrej 'SanTiago' Zajicek (email: santiago at crfreenet.org)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."
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